The apnea-hypopnea index is reported as the average number of apneas and hypopneas seen per hour of sleep.

The apnea-hypopnea index is reported as the average number of apneas and hypopneas seen per hour of sleep.

• A. Percentage of sleep time demonstrating apnea and hypopneas
• B. Percentage of sleep disrupted by apnea and hypopneas per hour
• C. Average number of apneas and hypopneas that occurred during the night
• D. Average number of apneas and hypopneas seen per hour of sleep

Answer: (D)

Understanding how the apnea-hypopnea index is defined: it is the average number of apneas and hypopneas per hour of sleep. This means you count all apneas and all hypopneas and divide by the total hours slept, giving a rate rather than a simple total. It’s not a percentage of sleep time with events, and it’s not just the total number of events seen during the night without accounting for how long the person slept. The calculation is AHI = (number of apneas + number of hypopneas) ÷ total sleep time in hours, which is why this per-hour rate best reflects the sleep-disruption burden.

Understanding how the apnea-hypopnea index is defined: it is the average number of apneas and hypopneas per hour of sleep. This means you count all apneas and all hypopneas and divide by the total hours slept, giving a rate rather than a simple total. It’s not a percentage of sleep time with events, and it’s not just the total number of events seen during the night without accounting for how long the person slept. The calculation is AHI = (number of apneas + number of hypopneas) ÷ total sleep time in hours, which is why this per-hour rate best reflects the sleep-disruption burden.